CN105340295B - Protection circuit and method for audio earthed circuit - Google Patents
Protection circuit and method for audio earthed circuit Download PDFInfo
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- CN105340295B CN105340295B CN201480034992.8A CN201480034992A CN105340295B CN 105340295 B CN105340295 B CN 105340295B CN 201480034992 A CN201480034992 A CN 201480034992A CN 105340295 B CN105340295 B CN 105340295B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/30—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters
- H03F1/305—Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in case of switching on or off of a power supply
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
- H03F1/52—Circuit arrangements for protecting such amplifiers
- H03F1/523—Circuit arrangements for protecting such amplifiers for amplifiers using field-effect devices
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/181—Low frequency amplifiers, e.g. audio preamplifiers
- H03F3/183—Low frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only
- H03F3/187—Low frequency amplifiers, e.g. audio preamplifiers with semiconductor devices only in integrated circuits
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/68—Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/687—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors
- H03K17/6871—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor
- H03K17/6874—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being field-effect transistors the output circuit comprising more than one controlled field-effect transistor in a symmetrical configuration
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/441—Protection of an amplifier being implemented by clamping means
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/444—Diode used as protection means in an amplifier, e.g. as a limiter or as a switch
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/555—A voltage generating circuit being realised for biasing different circuit elements
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K2217/00—Indexing scheme related to electronic switching or gating, i.e. not by contact-making or -breaking covered by H03K17/00
- H03K2217/0018—Special modifications or use of the back gate voltage of a FET
Abstract
In described example, charge pump (2) is powered by the first reference voltage (VDD) and generates control voltage signal (VCP) in control conductor (3).Ground switch circuit (15) includes depletion-mode transistor (MP 1), and the depletion-mode transistor (MP 1) has well region (4-1), the source electrode that is coupled to output conductor (6-1), is coupled to receive the grid of control voltage signal (VCP) and is coupled to the drain electrode of the second reference voltage (GND).Protecting circuit (17-1) includes the first and second depletion-modes protection transistor (MP3-1, MP4-1), with the respective gates for being coupled to control voltage signal (VCP) and has corresponding source electrode coupled to each other.First depletion-mode protection transistor (MP3-1) has the drain electrode for being coupled to the well region (4-1), and second depletion-mode protection transistor (MP4-1) has the drain electrode for the output signal (VQUT1) being coupled on the output conductor (6-1).
Description
Technical field
The present invention relates generally to electronic circuits, and in particular, be related to for audio earthed circuit protection circuit and
Method.
Background technique
Audio earthing switch may include depletion-mode MOS transistor to prevent the accumulation of charge.It is inserted when by headphone
Enter to generate audio signal device audio signal jack in when, this stored charge can cause electric discharge and it is associated ticking
Sound/sonic boom.The reason of electric discharge of this stored charge occurs is audio earthing switch and it connects circuit and has by electrostatic charge
Parasitic capacitance, inductance and the resistance of the influence of accumulation.This stored charge can be similar to common static discharge (ESD) and put like that
Electricity.For example, in audio ground switch circuit, when headphone to be connected to the connection circuit of audio earthing switch, this
Stored charge can static discharge to ground connection.The electric current as obtained by headset speaker resistance can cause such ticktack/
Sonic boom.
With reference to Fig. 1, conventional audio ground switch circuit 1 is implemented in IC chip, the IC chip packet
Containing being coupled in positive supply voltage VDDConventional charge pump 2 between system earth.Charge pump 2 generates output voltage on conductor 3
VCP.Charge pump 2 includes normal internal circuit, and the normal internal circuit is in VDDDrop below under-voltage (lock threshold) electricity
By V in the case where pressureCPDischarge into zero volt.Charge pump output voltage VCPP-channel MOS (metal oxidation is connected to by conductor 3
Object semiconductor) depletion-mode field effect transistor M P1 and MP2 gate electrode, depletion-mode field effect transistor M P1 and MP2 exist
VCPIt is typically located at when being in zero volt in its electrical conductive communication state.Work as VDDIt is when being in normal level (for example, 3.3 volts), then electric
Lotus pumps output voltage VCPIt is in increasing level (for example, at 7 volts).The source electrode of depletion-mode earthing switch transistor MP1 connects
To with audio information signal voltage VOUT1Conductor 6-1, and the source electrode of depletion-mode earthing switch transistor MP2 is connected to
With audio information signal voltage VOUT2Conductor 6-2.The source electrode of depletion-mode transistor MP1 and MP2 are limited to sufficiently low
Voltage, so that it is (in conjunction with raising charge pump voltage VCP) sufficiently large grid is generated to source electrode reverse bias voltage VGS, will consume
The state of mode transistor MP1 and MP2 operate conduction region from it and change to its cut-off region to the greatest extent.
Fig. 2, which shows to be directed in more detail, works as VDDThe connection associated with depletion-mode transistor MP1 of the case where when equal to zero
And signal.Depletion-mode transistor MP1 have the p-type source area that is formed in the N-shaped well region 4 of depletion-mode transistor MP1 and
Drain region.P-type source and N-shaped well region form associated parasitic diode D1 (it is with a large amount of parasitic capacitances), and exhaust
The p-type drain and N-shaped well region 4 of mode transistor MP1 forms associated parasitic diode D2, and (it also has a large amount of parasitic electricity
Hold).Fig. 5 is also referred to, N-shaped well region 4 is formed on p-substrate, and it is formed together associated parasitic substrate diode D3.
If MP1 is disconnected in its high impedance off state, the big negative voltage on conductor 6-1 is by forward bias substrate diode
D3-1, unless MP1 is conductive and therefore operates as earthing switch.If MP1 is in its electrical conductive communication state,
Audio signal can not exist, this is because audio signal by not across the grounding resistor Rl-1 of MP1 and low channel resistance (such as
Between 0.1 Ω and 1.0 Ω) parallel combination and generate.
The audio signal (such as with ± 2.63 volts range) of opposite large amplitude can be by conventional coding decoder (coding
Device-decoder) audio-frequency amplifier 8 in 11 generates on conductor 7.Across the resistive voltage divider coupling of audio signal, it is described
Resistive voltage divider includes: being coupled in output 7 and the V of audio-frequency amplifier 8OUT1(headphone 13) between conductor 6-1
The headphone resistance R2 of 16 Ω；And it is coupled in VOUT17 Ω grounding resistor R1 between conductor 6-1 and ground connection.Audio
Amplifier 8 is also using ground connection as reference.Grounding resistor (such as R1) and system earth are connected in series sometimes for audio engineer
To reduce or eliminate so-called ground noise.The lower divided output signal generated by audio-frequency amplifier 8 is as VOUT1It appears in and leads
On body 6-1, and the model that will there is ± 0.8 volt in the case where the depletion-mode transistor MP1 of Fig. 2 shutdown is non-switched
It encloses.However, the depletion-mode transistor MP1 of Fig. 2 is in its on-state, so its low-down channel resistance and ground connection electricity
Resistance device R1 is in parallel and causes VOUT1Substantially equal to zero.When depletion-mode field effect transistor M P1 is in its conductive or connection shape
When in state, audio signal there is usually no.Signal on conductor 6-1 is mended inside can be used in audio coder-decoder 11 providing
It repays.
Fig. 3 shows structure identical with Fig. 2, and difference is only that VDDNot equal to zero.On the contrary, VDDWith sufficiently big value with
Cause charge pump output voltage VCPAbout+7 volts, so the grid of depletion-mode transistor MP1 is to source voltage (VGS) amount
It is worth sufficiently high depletion-mode transistor MP1 to be switched in its high impedance status with complete switching off.In this case, amplify
Audio signal on device output conductor 7 usually exists, so VOUT1Complete ± 0.8 volt of output valve put by the audio on conductor 7
The partial pressure (coming from headphone resistance R2 and ground resistance R1) of big device output voltage generates on conductor 6-1.Fig. 2's and 3
The circuit of depletion-mode transistor MP1 can be used for the depletion-mode transistor MP2 of Fig. 1.
When not applying power to charge pump 2 (for example, working as VDDWhen=0), the conventional earthing switch integrated circuit of Fig. 1 to 3
There is provided the low-down resistance in parallel with grounding resistor R1, and whenever by enough VDDWhen electric power is applied to charge pump 2, figure
1 to 3 earthing switch integrated circuit also turns off depletion-mode transistor MP1, so that audio-frequency information can be generated on conductor 6-1
VOUT1And the ground connection sensing input of audio coder-decoder 11 is applied it to for processing.
N-shaped trap 4 and VOUT1Being directly connected to prevent of conductor 6-1 works as VOUT1It (include depletion mode for timing parasitic diode D1
PN junction between the p-type source and N-shaped well region 4 of formula transistor MP1) forward bias.Regrettably, if by depletion-mode crystalline substance
Body pipe MP1 is switched to its high impedance off state, then the AC signal V on conductor 6-1OUT1- 0.8 volt of part can cause to post
Raw diode D2 and D3 become forward bias, and a large amount of distortions are introduced into system audio signal V by thisOUT1In.
If loudspeaker or headphone 13 are inserted into personal computer in depletion-mode transistor MP1 shutdown
In the wear-type perforation of (or similar device), and if during non-audio event (such as when not providing desired audio signal
When) volume is opened and arrives its greatest level greatly, then can be heard from the headset speaker resistance indicated by resistor R2 angry
The audio frequency ground noise signal (for example, audio frequency buzz) of people.The noise reduction resistor R1 of 7 Ω in grounding path and
Headphone resistance R2 serves as divider together, and which reduce VOUT1The maximum negative voltage amplitude of oscillation magnitude (in this example
It is -0.8 volt) to prevent the substrate diode D3 (being formed by p-type source) and diode D2 of depletion-mode transistor MP1 (by n
Type well region 4 formation) forward bias.The grounding resistor R1 of 7 Ω reduce this non-audio event during audio drone sound and vibration
Width.R1 is grounded sense resistor and provides ground connection sensing input signal to coding decoder 11.This ground connection sensing input signal is used
In the noise for eliminating ground signalling.This function causes the signal of +/- 0.8 volt of relatively large magnitude to appear in VOUT1Conductor 6-1
On.
In general, ought be not by VDDWhen electric power is applied to charge pump 2, related to earth conductor and/or audio signal conductor 6-1
Some charge buildups occur in the parasitic capacitance of connection.As audio signal voltage VOUT1It is present on conductor 6-1 and is applied to Fig. 1
To 3 depletion-mode earthing switch transistor MPl drain electrode when, then the value on conductor 6-1 is -0.8 volt of VOUT1It appears in
On the cathode of substrate diode D3, thus forward bias substrate diode D3 and cause VOUT1In a large amount of distortions.It is anti-to help
Only discharging and thereby aiding in suddenly and prevent irritating ticktack/sonic boom (it can be by that will wear by headphone resistance R2
Formula earphone 13 is inserted into head phone jack to receive audio signal VOUT1Cause), depletion-mode transistor MPl (is in
In its on-state) it prevents build-up of static charges and inhibits or slow down putting for the electrostatic charge accumulated when being inserted into headphone 13
Electricity.
Summary of the invention
In described example, charge pump is powered by the first reference voltage and produces control voltage letter on control conductor
Number.Ground switch circuit includes depletion-mode transistor, and the depletion-mode transistor has well region, is coupled to output conductor
Source electrode is coupled to the grid for receiving control voltage signal and the drain electrode for being coupled to the second reference voltage.Protecting circuit includes the
One and second depletion-mode protect transistor, there are the respective gates for being coupled to control voltage signal and with coupled to each other
Corresponding source electrode.First depletion-mode protection transistor has the drain electrode for being coupled to well region, and the second depletion-mode protects crystal
Manage the drain electrode with the output signal being coupled on output conductor.
Detailed description of the invention
Fig. 1 is the schematic diagram of conventional audio ground switch circuit.
The depletion-mode field-effect with Fig. 1 for the case where Fig. 2 is for when transistor MP1 is in its on-state is brilliant
The associated parasitic diode of body pipe MPl and be coupled to transistor MP1 drain electrode resistive voltage divider schematic diagram.
Fig. 3 is to be directed to work as that enough supply voltage is applied to charge pump so that turning it off depletion-mode field effect transistor
The schematic diagram of the circuit of Fig. 2 of the case where when pipe MP1.
Fig. 4 is the schematic diagram of the audio ground switch circuit of example embodiment.
Fig. 5 is the integrated circuit sectional view of the p-type depletion-mode transistor MP1 of Fig. 4, shows source area and drain region, n
Type well region, p-substrate and associated parasitic diode.
Specific embodiment
With reference to Fig. 4, ground switch circuit 15 includes circuit 17-1, and circuit 17-1 is used for: (a) prevent charge buildup, and by
This prevents after discharge of the charge accumulated under all operating conditions in depletion-mode earthing switch transistor MP1 and MP2, and
The quality of desired audio signal is not damaged；(b) prevent circuit 15 (it receives audio signal) from making audio signal VOUT1Distortion；And
(c) when being inserted into headphone in the jack for receiving audio signal, preventing originally can be by the electricity that accumulates in circuit 15
Sonic boom caused by the electric discharge of lotus.In addition, circuit 15 makes it possible for high electrical resistance grounding resistor without causing by circuit 15
The distortion of received audio signal.
In one embodiment, it is conducted on output conductor 6-1 from earthed circuit 10 (for example, AC signal circuit) defeated
Signal V outOUT1The signal path of (for example, AC output signal).Charge pump 2 is by the first reference voltage VDDIt powers and in control conductor
Control voltage signal V is generated on 3CP.Control voltage signal VCPIn the first reference voltage VDDThere is phase when being in relatively low level
To low value, and in the first reference voltage VDDRelatively high value is increased to when being in relatively high level.Ground switch circuit
15 include depletion-mode transistor MPl, and the depletion-mode transistor has the source electrode, coupled for being coupled to output conductor 6-1
Voltage signal V is controlled to receiveCPGrid and be coupled to the drain electrode of the second reference voltage GND.Depletion-mode transistor MPl has
Well region 4-1, the first parasitic diode D1-1 (it includes the PN junctions between the source electrode 14 of Fig. 5 and the well region 4-1 of Fig. 5), second are posted
Raw diode D2-1 (it includes the PN junctions between the drain electrode 16 of Fig. 5 and the well region 4-1 of Fig. 5) and third parasitic diode D3-1
(it includes the PN junctions between the substrate 19 of Fig. 5 of well region 4-1 and adjacent well region 4-1).Protecting circuit 17-1 includes first and the
Two depletion-modes protect transistor MP3-1 and MP4-1, have the control voltage signal V being coupled on control conductor 3CPPhase
It answers grid and has and be coupled to conductor 5-1 (its n for being connected to the first and second depletion-modes protection transistor MP3-1 and MP4-1
Type well region) corresponding source electrode.First depletion-mode protection transistor MP3-1 has the drain electrode for being coupled to well region 4-1, and second
Depletion-mode protection transistor MP4-1 has the output signal V being coupled on output conductor 6-1OUT1Drain electrode.Level shift electricity
Road MN-1 is coupled between well region 4-1 and control conductor 3.
For example, in the embodiments described, level shift circuit MN-1 is operated as diode, the diode warp
Coupling is according to control voltage signal VCPWell region charging is given, to prevent from exporting and remaining substrate diode reverse bias
Signal VOUT1Distortion.Therefore, this diode is diode link enhancement mode transistor MN-1, includes source electrode, is coupled
To well region 4-1；And grid and drain electrode, it is coupled to control 3 (V of conductorCP).In the embodiments described, the first output letter
Number VOUT1For audio frequency signal.
In one embodiment, signal path is (defeated it includes being coupled in first comprising amplifier 8-1, resistive voltage divider
Conductor 6-1 (V outOUT1) and the second reference voltage GND between ground noise resistor R1-1, and be coupled in amplifier 8-1
Output 7-1 and the first output conductor 6-1 (VOUT1) between external headset 13-1 loudspeaker resistance R2-1).
In one embodiment, ground noise resistor R1-1 has the resistance of about 7 Ω, and resistance R2-1 has the value of about 16 Ω.
In one embodiment, the first depletion-mode transistor MP1 is p-channel MOS depletion-mode transistor, and two poles
Pipe link enhancement mode transistor MN-1 is n-channel enhancement mode MOS transistor.The channel width of enhancement mode transistors MN-1
The channel width and channel length ratio of the first depletion-mode transistor MP1 are substantially less than with channel length ratio.
In one embodiment, well region 4-1 is the N-shaped well region of adjacent p-substrate 19.As the first reference voltage VDDSubstantially
When more than relatively low level (so the first depletion-mode transistor MP1 being in its off state), diode link enhancement
Well region 4-1 is charged to by mode transistor MN-1 is equal to control voltage signal VCPSubtract diode link enhancement mode transistor
The forward threshold voltage V of MN-1TVoltage.When the first depletion-mode transistor MP1 is in its on-state, first and
The protection of two depletion-modes transistor MP3-1 and MP4-1 cooperate so that well region 4-1 to be charged to the voltage level of the first output conductor 3
(VOUT1), and when the first depletion-mode transistor MP1 is in its off state, parasitic diode D7-1 is (with the second consumption
Mode protection transistor MP4-1 is associated to the greatest extent) prevent charge from escaping from well region 4-1.In one embodiment, diode connection increases
The body electrode of strong mode transistor MN-1 is connected to the second reference voltage GND.In one embodiment, well region 4-1 is to be placed in p
N-type semiconductor layer in type semiconductor substrate, and the source electrode 14 of the first depletion-mode transistor MP1 and drain electrode 16 are well region 4-
It p-type area in 1 and is separated by the p-type channel region 20 in well region 4-1.
In one embodiment, the first negative electricity voltage protection circuit 17-1 operation with: be inserted by headphone 13-1
Ticktack/sonic boom is prevented when being connected in the jack of the first output conductor 6-1；In the first output signal VOUT1It is not present and first
Depletion-mode transistor MP1 be in off state in the case where from the first output conductor 6-1 eliminate audio drone acoustical signal.
In one embodiment, if the first reference voltage VDDIt is in relatively low level, then charge pump 2 is operated such that
Make to control voltage signal VCPIt is approximately equal to zero.
In one embodiment, the second output signal V is conducted in second signal channel on the second output conductor 6-2OUT2, and
And second depletion-mode transistor MP2 have be coupled to the second output conductor 6-2 source electrode and with the first depletion-mode transistor
MP1 substantially the same structure, and the second protection circuit 17-2 and the first protection circuit 17-1 are substantially the same.
In one embodiment: (a) depletion-mode earthing switch transistor MP1 and the protection of the first and second depletion-modes
Transistor MP3-1 and MP4-1 are p-type channel depletion-mode transistor；And (b) diode link enhancement mode transistor MN-1
For n-channel enhancement mode transistors.
Fig. 4 shows the embodiment of the circuit 10 comprising ground switch circuit 15, and the ground switch circuit includes again: first
With the second audio signal channel；And negative electricity voltage protection circuit 17-1 and 17-2.Negative electricity voltage protection circuit 17-1 and 17-2 are prevented
The depletion-mode earthing switch transistor MP1 of the negative part forward bias ground switch circuit 15 of audio signal in two channels
With the endophyte PN junction (for example, PN diode) in MP2, and thus prevent first as caused by the negative part of audio signal
With the distortion of the audio signal in the second audio signal channel.
First audio signal channel includes the audio-frequency amplifier 8-1 that audio output signal is generated on conductor 7-1, and is wrapped
(V is generated it includes the output 7-1 for being coupled in amplifier 8-1 and on it containing resistive voltage dividerOUT1Output conductor 6-1 it
Between speaker resistor R2-1).Audio-frequency amplifier 8-1 is included in conventional coding decoder 11-1.Coding decoder 11-1 tool
There is the ground connection sensing input for being connected to output conductor 6-1.Signal on conductor 6-1 can be used in audio coder-decoder 11 mentioning
For internal compensation.Ground noise resistor R1-1 is connected to VOUT1Between conductor 6-1 and ground connection.Grounding resistor R1-1 can be 7
Ω and at depletion-mode transistor MPl in its high impedance off state (if being present in the first audio without audio signal
In channel) when in VOUT1It is upper to generate the signal for allowing coding decoder 11-2 to reduce ground noise (such as buzz).It is in it
The low impedance path of depletion-mode transistor MP1 in on-state reduces pop noise/ticking noise.Pass through ground resistance
Circuit in R1-1 and audio coder-decoder 11-1 reduces audio buzz.The headphone of external headset 13-1
Speaker resistor R2 can be 16 Ω, and grounding resistor R1-1 can be 7 Ω.
Similarly, the second audio signal channel includes the audio-frequency amplifier 8- that audio output signal is generated on conductor 7-2
2, and include that resistive voltage divider (generates it includes the output 7-2 for being coupled in amplifier 8-2 and on it the second audio signal
The audio output signal V in channelOUT2Output conductor 6-2 between another external headset 13-2 another wear-type ear
Machine speaker resistor R2-2).Grounding resistor R1-2 is connected between output conductor 6-2 and ground connection.
In addition, ground switch circuit 15 includes to be coupled in positive supply voltage VDDConventional charge pump 2 between system earth.
Charge pump 2 generates output voltage V on control conductor 3CP.Charge pump 2 is in VDDDrop below the feelings of its under-voltage lock threshold
By V under conditionCPDischarge into zero volt.Charge pump output voltage VCPIt is coupled to p-channel MOS (metal oxide by controlling conductor 3
Semiconductor) depletion-mode field-effect earthing switch transistor MP1 and MP2 gate electrode, depletion-mode field-effect earthing switch is brilliant
Body pipe MP1 and MP2 are in VCPIt is typically located at when equal to zero volt in its conductive or on-state.Work as VDDIt is in normal level (example
Such as, 3.3 volts) when, then charge pump output voltage VCPSubstantial higher level, the substantially higher electricity are increased to from 0 volt
Flat is about+7 volts in the example in figure 4.Two or more charge pumps in parallel may be selected to support two or more differences
The V of voltage levelDD, and charge pump can have various different frameworks, such as closed loop charge pump architecture.In addition, if high voltage
The V of levelCPBy user, as relatively high supply voltage, (it can provide and control the V on conductor 3 through switchingCPSubstantially etc.
The control signal of effect) it is supplied from outside, then charge pump can be omitted.However, in many cases, this mode will be very not
It corresponds to reality and valuableness.
The source electrode of depletion-mode transistor MP1 is connected to VOUT1Conductor 6-1, and the source of depletion-mode transistor MP2
Pole is connected to VOUT2Conductor 6-2.The drain electrode of depletion-mode transistor MP1 and MP2 are connected to ground connection.Depletion-mode transistor
MP1 has the p-type source area 14 and p-type drain area 16 being formed in the N-shaped well region 4-1 of depletion-mode transistor MP1, such as Fig. 5
Shown in, and depletion-mode transistor MP2 has similar structures in the well region of its own.The n of depletion-mode transistor MP1
Type well region 4-1 is placed on p-substrate 19, as shown in Figure 5.The p-type source 14 and N-shaped well region of depletion-mode transistor MP1
4-1 forms associated parasitic diode D1-1 (it is with a large amount of parasitic capacitances), and the p-type leakage of depletion-mode transistor MP1
Polar region 16 and N-shaped well region 4-1 form associated parasitic diode D2-1 (it also has a large amount of parasitic capacitances).N-shaped well region 4-1 and
P-substrate is formed together the associated parasitic substrate diode D3-1 with a large amount of parasitic capacitances.
In the integrated circuit sectional view of Fig. 5, p-channel depletion-mode transistor MP1 includes to be formed in N-shaped well region 4-1
P-type source area 14 and p-type drain area 16, the N-shaped well region 4-1 is formed on p-substrate 19.Gate oxide 18 is formed in
On p-type channel region 20, the p-type channel region is tightly attached to 18 lower section of gate oxide and extends to p from the edge of p-channel source area 14
The edge in channel drain area 16.Gate electrode 21 is formed on the upper surface of gate oxide 18.The contact zone N+ 23 allows and N-shaped trap
The low resistance contact of area 4-1, and the area P+ 24 allows the low resistance contact with P+ substrate 19.Parasitic diode D1-1 includes source
PN junction between polar region 14 and well region 4-1.Parasitic diode D2-1 includes the PN junction between drain region 16 and well region 4-1.Substrate
Diode D3-1 includes the PN junction between substrate zone 19 and well region 4-1.
In Fig. 4, output of the audio-frequency amplifier 8-1 on conductor 7-1 is the audio signal of opposite large amplitude (for example, tool
There is ± 2.63 volts of range).Lower frequency dividing output voltage on the conductor 7-1 of audio-frequency amplifier 8-1 is as VOUT1It appears in and leads
On body 6-1, and will be turned off in depletion-mode transistor MP1 and it is non-switched in the case where with ± 0.8 volt of range.So
And if depletion-mode transistor MP1 is in its on-state, low-down channel resistance and grounding resistor R1
Parallel connection simultaneously causes VOUT1Magnitude be not enough to cause in parasitic diode appoint whichever forward bias.
If VDDWith sufficiently big value to cause charge pump output voltage VCPIt is about+7 volts, then it causes to exhaust
The magnitude of mode earthing switch transistor MP1 grid sufficiently high complete switches off depletion-mode transistor MP1 (example to source voltage
Such as, MP1 is switched in its high impedance status).It therefore, can be by the V on conductor 6-1OUT1Complete ± 0.8 volt of lower frequency dividing it is defeated
Value, which is applied to, out is connected to amplifier output conductor 7-1 and VOUT1Wear-type resistance R2-1 between conductor 6-1.
In addition, ground switch circuit 15 includes negative electricity voltage protection circuit 17-1, the negative electricity voltage protection circuit ensures to exhaust
The well region 4-1 of mode transistor MP1 is biased always, so that no one of its associated parasitic diode becomes forward bias
It sets.As long as N-shaped well region 4-1 is connected to ceiling voltage associated with MP1, related to depletion-mode earthing switch transistor MP1
The parasitic diode of connection just reverse bias always.Regrettably, if ceiling voltage is directly connected to as in Fig. 1 to 3
VOUT1, then ceiling voltage not can be coupled to well region 4-1 always.Therefore, in this case, if depletion-mode transistor
MP1 is in VOUT1It is in its off state when being in its minimum -0.8 volt of level, then substrate diode D3-1 will become just
To biasing.Unacceptable distortion will be introduced into V by thisOUT1In.Compared with the circuit of Fig. 1 to 3, the well region biasing circuit of Fig. 4
17-1 substantially avoids this problem.
Negative electricity voltage protection circuit 17-1 includes that p-channel depletion-mode protects transistor MP3-1, its drain electrode is made to be connected to trap
Area 4-1 makes its grid be connected to charge pump output voltage VCPConductor 3 and make its source electrode be connected to another p-channel depletion-mode to protect
Protect the source electrode of transistor MP4-1.Conductor 5-1 is connected to N-shaped well region, and be connected to depletion-mode protection transistor MP3-1 and
The source electrode of both MP4-1.All depletion-mode transistor MP1 and MP2 have the corresponding well region of its own, and depletion-mode is protected
Shield transistor MP3-1 and MP4-1 can share shared well region or alternatively may be formed at linked together by conductor 5-1 it is independent
In well region.The grid of depletion-mode protection transistor MP4-1 is connected to VCP, and its drain electrode is connected to VOUTIConductor 6-1.It exhausts
It includes associated parasitic diode D6-1 that mode, which protects transistor MP3-1, and parasitic diode D6-1 makes its anode be connected to N-shaped trap
Area 4-1 and make its cathode by conductor 5-1 be connected to depletion-mode protect transistor MP3-1 well region.Parasitic diode D4-1
So that its anode is connected to the source electrode of depletion-mode protection transistor MP3-1 and its cathode is also made to be connected to conductor 5-1.Parasitic two poles
By conductor 5-1 short circuit occurs for pipe D4-1 and D5-1.Parasitic diode D5-1 makes its anode be connected to depletion-mode protection crystal
The source electrode of pipe MP4-1 and its cathode is made to be connected to conductor 5-1.Parasitic diode D7-1 makes its anode pass through VOUT1Conductor 6-1 connects
It is connected to the drain electrode of depletion-mode protection transistor MP4-1 and its cathode is made to be connected to conductor 5-1.Depletion-mode protects transistor
The channel width and channel length ratio of MP3-1 and MP4-1 is smaller than the correspondence ratio of depletion-mode protection transistor MP1 and MP2
Much, this is because it biases well region 4-1 but does not need to draw any signal code.
In Fig. 4, the grid of n-channel enhancement mode transistors MN-1 and drain electrode are connected to VCPConductor 3, and diode connects
The source electrode for meeting transistor MN-1 is connected to well region 4-1.The body electrode of diode connection n-channel enhancement mode MOS transistor MN-1
It is connected to ground connection.
If by VDD=0 is applied to charge pump 2, then VCPIt also is 0 volt, and therefore VOUT1Pass through the connection channel of MP1
Resistance is coupled to system earth.For example, if not applying between the grid and source electrode of depletion-mode earthing switch transistor MP1
VGSVoltage is turned off, then MP1 and depletion-mode protection transistor MP3-1 and MP4-1 are in its on-state, and N-shaped
Well region 4-1 is connected to V by the connection resistance of depletion-mode protective resistor MP3-1 and MP4-1OUT1(its in circuit most
High voltage).Therefore, the non-forward bias of parasitic diode.
However, if biggish V will be worthDD(for example, 3.3 volts), which are applied to, powers on charge pump 2, then (in this example)
It can be by VCPAbout+7 volts are increased, and then depletion-mode transistor MP1 and depletion-mode protect transistor MP3-1 and MP4-1
It is in its high impedance off state.Therefore, the ceiling voltage in circuit is (for example, VOUT1) be not useable for biasing N-shaped well region 4-
1, so as demonstrated like that using enhancement mode transistors MN-1 (because of VCPEqual to about 7 volts, and the voltage of well region 4-1
Less than amount 7-VTVolt).Well region charging enhancement mode transistors NM-1 will conduct electric current and be charged to N-shaped well region 4-1 up to
VCP-VTAnd then turn off, so that it is guaranteed that all equal reverse bias of parasitic diode D1-1, D2-1 and D2-3.
When charge pump 2 is not powered (for example, if VDD=0), because whenever VDDCharge pump 2 is automatically by V when=0CPIt puts
Electricity is to ground connection so VOUT1It effectively is shorted to ground connection, and this causes depletion-mode transistor MP1 to be in its electrical conductive communication state
In.Therefore, diode link enhancement mode n-channel transistor MN-1 can not be in its on-state because of reverse bias,
Or in the case where the worst, source electrode, grid and the voltage of drain electrode of enhancement mode well region charging transistor MN-1 is equal to zero volt
It is special.In this case, depletion-mode protection transistor MP3-1 and MP4-1 allow electric current to flow through depletion-mode transistor
MP3-1 and MP4-1, this is because its grid is under ground voltage, so both transistor MP3-1 and MP4-1 are in it and lead
It electrically connects in state.Therefore, N-shaped well region 4-1 can be biased to VOUT1Voltage level, this is in VOUT1Be in or close to it is minimum-
Any forward bias for appointing whichever in substrate diode D3-1 or other parasitic diodes is prevented when 0.8 volt of level.
When charge pump 2 passes through VDDWhen=3.3 volts of power supplies, the N-shaped well region 4-1 of depletion-mode transistor MP1 is in the short time
Interim is charged to V by diode link enhancement mode transistor MN-1CP-VTVolt, wherein VTFor diode link enhancement
The forward threshold voltage of mode transistor MN-1.Short time interval is for VCPIncrease to from 0 volt and is up to about+7 volts of transition
Time.Short time interval be also diode link enhancement mode transistor MN-1 resistance and with depletion-mode transistor MP1 phase
The time constant of the capacitor of associated parasitic diode D1-1, D2-1 and D2-3.Enhancement mode transistors MN-1 will be in VCPRise
When connect continue shorter time quantum, this allow electric current from charge pump 2 flow through conductor 3 and enter N-shaped well region 4-1, thus by trap
Area 4-1 and its parasitic capacitance are charged to VCP-VT。
If omitting diode connected transistor MN-1, N-shaped well region 4-1 will be charged to lucky VCP, and exhaust
Mode protection transistor MP3-1 and MP4-1 will not be turned off (because the drain voltage of depletion-mode protection transistor MP3-1 will
It is identical as its grid voltage).Therefore, gate mode protection transistor MP3-1 and MP4-1 will be turned off never, so will deposit always
From output VOUT1By protecting the current path of depletion-mode transistor MP3-1 and MP4-1, thus cause VOUT1A large amount of distortions.
The effect of diode connected transistor MN-1 is the voltage in the drain electrode for reduce depletion-mode protection transistor MP3-1, so two
A depletion-mode protection transistor MP3-1 and MP4-1 can be turned off.Parasitic capacitance associated with well region 4-1 is connected by diode
Enhancement mode transistors MN-1 charging is connect until it turns off its own, and later, diode link enhancement mode is brilliant
Body pipe MN-1 supplies the insignificant magnitude of current only to keep well region 4-1 to be charged to VCP-VTLevel.
Two back-to-back depletion-mode transistor MP3-1 and MP4-1 (rather than only one) are available, this is because individually
Depletion-mode transistor (for example, MP3-1) will lack the suitable method of biasing well region 5-1.For example, if well region 5-1 directly connects
It is connected to VOUT1, then the V on conductor 6-1OUT1Voltage will be less than the voltage of well region 4-1, this is because (in this example) VOUT1
V is charged to for 3.3 volts and well region 4-1CP(it is+7V in this example) subtracts the connection electricity of diode connected transistor MN-1
Press VT.Therefore, parasitic diode D6-1 will become forward bias and electric current is allowed to flow to V from charge pump 2OUT1In conductor 6-1.
For anti-situation here, back-to-back depletion-mode protection transistor MP3-1 and MP4-1 allow well region 4-1 to be charged to VCP-VTElectricity
It is flat.Reverse bias parasitic diode D7-1 then prevents to appoint whichever to escape from well region 5-1 in the charge, this is because two poles
Pipe D7-1 reverse bias.
In addition, ground switch circuit 15 includes negative electricity voltage protection circuit 17-2, the negative electricity voltage protection circuit ensures to exhaust
The well region 4-2 of mode earthing switch transistor MP2 is biased always, so that parasitism two associated with depletion-mode transistor MP2
No one of pole pipe becomes forward bias.The negative electricity voltage protection circuit 17-2 of Fig. 4 substantially avoids this problem, this be because
For the structurally and operationally structurally and operationally substantially the same with well region biasing circuit 17-1 of well region biasing circuit 17-2.
Described embodiment substantially avoids the distortion of the audio signal in one or more audio signal channels, simultaneously
Allow: (a) when not by VDDElectric power applies the V of positive level when being applied to charge pump 2OUT1；And (b) when by VDDElectric power is applied to charge
Apply the V of positive and negative level when pumping 2OUT1.This enables system engineer to be used to pass through tolerance for higher external ground resistance
The resulting larger negative voltage amplitude of oscillation realizes noise immunity.
Modification be in the embodiments described it is feasible, and other embodiments be within the scope of the claims can
Capable.For example, described embodiment is only how inherently to make output short-circuit until earthing switch from earthing switch transistor
Until transistor wakes up in response to wake-up switch control (such as to give pump charging).Earthing switch Prective circuit for transistor is at it
Middle bipolar signal (for example, relative to ground connection with reference to the signal with both positive value and negative value) will be by always (including when ground connection is opened
Transistor is closed when turning on and off) it can use in the case where accurate driving.For example, negative voltage is for being applied to accurate motor driven electricity
Road is to prevent the minor error angle offset (similar to ticktack/sonic boom in described voice applications) of the position of motor can
It is important.Also, described embodiment during the charging of device the good driving signal of specified control it is various other
It is available in.In addition, if different types of diode (for example, common PN diode) provides suitable voltage drop simultaneously
And level shift circuit can be used for adjusting charge pump output voltage if appropriate, then this diode can be used to realize enhancing mould
The charge function of formula well region charging transistor MN-1.
Claims (20)
1. a kind of from earthed circuit comprising:
Signal path is used to conduct output signal on output conductor；
Charge pump is powered by the first reference voltage to generate control voltage signal, the control voltage letter on control conductor
There is the first value in the case where the first level and at first reference voltage the number at first reference voltage
There is second value, wherein first level is lower than the second electrical level, and first value is lower than institute in the case where two level
State second value；
Ground switch circuit, it includes depletion-mode transistor, the depletion-mode transistor is led with the output is coupled to
The source electrode of body is coupled to the grid for receiving the control voltage signal and the drain electrode for being coupled to the second reference voltage；It is described
Depletion-mode transistor has the first well region, the comprising the PN junction between the source electrode and first well region first parasitic two poles
Pipe, comprising it is described drain electrode first well region between PN junction the second parasitic diode and comprising first well region with
The third parasitic diode of PN junction between the substrate of adjacent first well region；And
Circuit is protected, it includes: the first and second depletion-modes protect transistor, with corresponding second well region, are coupled to institute
It states the respective gates of the control voltage signal on control conductor and has coupled to each other and be coupled in second well region
The corresponding source electrode of at least one, wherein first depletion-mode protection transistor has the leakage for being coupled to first well region
Pole, and second depletion-mode protection transistor has the leakage for the output signal being coupled on the output conductor
Pole；And level shift circuit, it is coupled between first well region and the control conductor.
2. circuit according to claim 1, wherein the level shift circuit is diode link enhancement mode transistor,
The diode link enhancement mode transistor, which has the source electrode for being coupled to first well region and is coupled to the control, leads
The grid of body and drain electrode.
3. circuit according to claim 2, wherein the output signal is audio frequency signal.
4. circuit according to claim 1, wherein the signal path is led comprising amplifier, comprising being coupled in the output
The resistive voltage divider of ground noise resistor between body and second reference voltage and it is coupled in the amplifier
The resistance of the loudspeaker of external headset between output and the output conductor.
5. circuit according to claim 4, wherein the ground noise resistor has the resistance of 7 Ω, and wherein institute
The resistance for stating loudspeaker has the value of 16 Ω.
6. circuit according to claim 2, wherein the depletion-mode transistor and first and second depletion mode
It is p-channel MOS depletion-mode transistor that formula, which protects transistor, and the diode link enhancement mode transistor is n-channel
Enhancement mode MOS transistor.
7. circuit according to claim 2, wherein the channel width and ditch of the diode link enhancement mode transistor
Road length ratio is less than the channel width and channel length ratio of the depletion-mode transistor.
8. circuit according to claim 4, wherein first well region is the N-shaped well region of adjacent p-substrate.
9. circuit according to claim 2, wherein when first reference voltage is more than first level, described two
First well region is charged to and subtracts the diode equal to the control voltage signal by pole pipe link enhancement mode transistor
The voltage of the forward threshold voltage of link enhancement mode transistor.
10. circuit according to claim 1, wherein first depletion-mode protection transistor and second depletion mode
Formula protects transistor cooperation first well region is charged to institute in its on-state at the depletion-mode transistor
The voltage level of output conductor is stated, and is consumed in its off state by with described second at the depletion-mode transistor
The mode protection associated parasitic diode of transistor prevents charge from escaping from first well region to the greatest extent.
11. circuit according to claim 2, wherein the body electrode of the diode link enhancement mode transistor is connected to
Second reference voltage.
12. circuit according to claim 1, wherein first well region is the N-shaped half being placed on p-type semiconductor substrate
Conductor layer, and the source electrode of the depletion-mode transistor and the drain electrode for the p-type area in first well region and are led to
The p-type channel crossed in first well region distinguishes.
13. circuit according to claim 4, wherein the protection circuit operation by the headphone to be inserted into
Ticktack/sonic boom is prevented when being connected to the jack of the output conductor.
14. circuit according to claim 1, wherein if first reference voltage is in the first level, it is described
Charge pump operation is to cause the control voltage signal to be equal to zero.
15. circuit according to claim 1, wherein the signal path is the first signal path, the output signal is
First output signal, the output conductor are the first output conductor, and the protection circuit is first to protect circuit, and described exhaust
Mode transistor is the first depletion-mode transistor, and further comprising: second signal channel, is used in the second output
The second output signal is conducted on conductor, wherein the ground switch circuit includes the second depletion-mode transistor, second consumption
Mode transistor with the source electrode for being coupled to second output conductor and has and the first depletion-mode transistor phase to the greatest extent
Same structure, and wherein the ground switch circuit includes the second protection circuit, the second protection circuit and described first
Protect circuit identical.
16. a kind of method for preventing the distortion as the output signal caused by the ground switch circuit in ground switch circuit, institute
The method of stating includes:
The output signal is provided on output conductor；
Operation is by the charge pump that the first reference voltage is powered to generate control voltage signal, the control voltage on control conductor
Signal at first reference voltage in the case where the first level have the first value and at first reference voltage
There is second value, wherein first level is lower than the second electrical level, and first value is lower than in the case where second electrical level
The second value；
The control voltage signal is applied to the grid of depletion-mode earthing switch transistor, the depletion-mode earthing switch
Transistor is with the source electrode for being coupled to the output conductor and has the drain electrode for being coupled to the second reference voltage, the depletion-mode
Earthing switch transistor has the first well region, the comprising the PN junction between the source electrode and first well region first parasitic two poles
Pipe, comprising it is described drain electrode first well region between PN junction the second parasitic diode and comprising first well region with
The third parasitic diode of PN junction between the substrate of adjacent first well region；
The control voltage signal on the control conductor is coupled to the phase of the first and second depletion-modes protection transistor
Answer grid, the first and second depletion-modes protection transistor has corresponding second well region and coupled to each other and be coupled to institute
The corresponding source electrode of at least one of second well region is stated, wherein first depletion-mode protection transistor, which has, is coupled to described the
The drain electrode of one well region, and second depletion-mode protection transistor has the output being coupled on the output conductor
The drain electrode of signal；And
Level shift circuit is coupled between first well region and the control conductor.
17. according to the method for claim 16, further comprising: operation first depletion-mode protection transistor and
Second depletion-mode protection transistor at the depletion-mode earthing switch transistor in its on-state by institute
The voltage level that the first well region is charged to the output conductor is stated, and at it at the depletion-mode earthing switch transistor
Prevent charge from described the by with the associated parasitic diode of second depletion-mode protection transistor when off state
The evolution of one well region.
18. according to the method for claim 16, wherein the level shift circuit is diode link enhancement mode crystal
Pipe, and the method further includes: when first reference voltage be more than first level when operate the diode
Link enhancement mode transistor subtracts the diode company equal to the control voltage signal being charged to first well region
Connect the voltage of the forward threshold voltage of enhancement mode transistors.
19. according to the method for claim 18, further comprising: using p-channel depletion-mode transistor described in
Depletion-mode earthing switch transistor and as first and second depletion-mode protect transistor；With use n-channel to enhance
Mode transistor is as the diode link enhancement mode transistor.
20. a kind of circuit for preventing the distortion of AC output signal as caused by the ground switch circuit in AC signal circuit, packet
It includes:
For providing the device of the AC output signal on output conductor；
Charge pump is powered by the first reference voltage to generate control voltage signal, the control voltage letter on control conductor
There is the first value in the case where the first level and at first reference voltage the number at first reference voltage
There is second value, wherein first level is lower than the second electrical level, and first value is lower than institute in the case where two level
State second value；
For the control voltage signal to be applied to the device of the grid of depletion-mode earthing switch transistor, the depletion mode
Formula earthing switch transistor is with the source electrode for being coupled to the output conductor and has the drain electrode for being coupled to the second reference voltage, institute
Depletion-mode earthing switch transistor is stated with well region, the first parasitism two comprising the PN junction between the source electrode and the well region
Pole pipe, the second parasitic diode comprising the PN junction between the drain electrode and the well region and include the well region and adjacent institute
State the third parasitic diode of the PN junction between the substrate of well region；
For the well region to be charged to the output in its on-state at the depletion-mode earthing switch transistor
The voltage level of conductor, and at the depletion-mode earthing switch transistor in its off state by with depletion-mode
The device that the protection associated parasitic diode of transistor prevents charge from escaping from the well region；And
For the well region to be charged to equal to the control voltage when first reference voltage is more than first level
Signal subtracts the voltage of the forward threshold voltage of diode link enhancement mode transistor, so that the depletion-mode earthing switch
Transistor is in the device in its off state.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13/920,302 | 2013-06-18 | ||
| US13/920,302 US9136796B2 (en) | 2013-06-18 | 2013-06-18 | Negative audio signal voltage protection circuit and method for audio ground circuits |
| PCT/US2014/043013 WO2014205120A1 (en) | 2013-06-18 | 2014-06-18 | Protection circuitry and methods for audio ground circuits |
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| Publication Number | Publication Date |
|---|---|
| CN105340295A CN105340295A (en) | 2016-02-17 |
| CN105340295B true CN105340295B (en) | 2019-05-14 |
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|---|---|---|---|
| CN201480034992.8A Active CN105340295B (en) | 2013-06-18 | 2014-06-18 | Protection circuit and method for audio earthed circuit |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US9136796B2 (en) |
| EP (1) | EP3011756B1 (en) |
| CN (1) | CN105340295B (en) |
| WO (1) | WO2014205120A1 (en) |
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| US9854355B2 (en) * | 2012-06-10 | 2017-12-26 | Apple Inc. | Grounding circuit for alternate audio plug designs |
| WO2018129096A1 (en) * | 2017-01-03 | 2018-07-12 | Synaptics Incorporated | Hum reduction circuit and method |
| CN110381409B (en) * | 2019-08-13 | 2021-11-26 | 高创(苏州)电子有限公司 | Control panel of display, driving method thereof and display |
| CN114123146B (en) * | 2020-08-31 | 2023-08-22 | 华为技术有限公司 | Audio port processing circuit and surge protection method |
| CN113825057B (en) * | 2021-08-16 | 2024-02-27 | 广东朝阳电子科技股份有限公司 | Bluetooth headset charging box boost circuit |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012125767A1 (en) * | 2011-03-14 | 2012-09-20 | Qualcomm Incorporated | Charge pump electrostatic discharge protection |
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| GB9213992D0 (en) | 1992-07-01 | 1992-08-12 | Raychem Ltd | Remotely actuated switch and protection circuit |
| DE10314601B4 (en) * | 2003-03-31 | 2005-04-21 | Infineon Technologies Ag | Semiconductor circuit with a protection circuit against reverse polarity or overvoltage or undervoltage at the output |
| EP1599067B1 (en) * | 2004-05-21 | 2013-05-01 | Epcos Pte Ltd | Detection and control of diaphragm collapse in condenser microphones |
| US9402128B2 (en) * | 2012-04-11 | 2016-07-26 | James K. Waller, Jr. | Adaptive rail power amplifier technology |
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2013
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| WO2012125767A1 (en) * | 2011-03-14 | 2012-09-20 | Qualcomm Incorporated | Charge pump electrostatic discharge protection |
Also Published As
| Publication number | Publication date |
|---|---|
| EP3011756B1 (en) | 2021-02-24 |
| US20140369520A1 (en) | 2014-12-18 |
| EP3011756A1 (en) | 2016-04-27 |
| EP3011756A4 (en) | 2017-03-01 |
| US9136796B2 (en) | 2015-09-15 |
| CN105340295A (en) | 2016-02-17 |
| WO2014205120A1 (en) | 2014-12-24 |
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